diff --git a/macros.pyproject b/macros.pyproject
index 1d2fc43..9e55089 100644
--- a/macros.pyproject
+++ b/macros.pyproject
@@ -29,7 +29,7 @@ echo 'python3dist(pytoml)'
 # setuptools assumes no pre-existing dist-info
 rm -rfv *.dist-info/
 if [ -f %{__python3} ]; then
-  RPM_TOXENV=%{toxenv} %{__python3} -I %{_rpmconfigdir}/redhat/pyproject_buildrequires.py %{?**}
+  RPM_TOXENV="%{toxenv}" %{__python3} -I %{_rpmconfigdir}/redhat/pyproject_buildrequires.py %{?**}
 fi
 }